1. Field of the Invention
This invention relates to an endoscope apparatus wherein the insertable part can be housed as wound up on a drum.
2. Related Art Statement
Recently, there has been extensively utilized a medical endoscope whereby organs within a body cavity can be observed by inserting an elongate insertable part into the body cavity or various treatments can be made as required by using treating instruments inserted through a treating instrument channel. Also, in the industrial field, there has been extensively utilized an industrial endoscope whereby the interior of a boiler, turbine, engine or chemical plant can be observed or inspected.
There is such industrial endoscope as, for example, a Borehole Scope System (trade name) made by Furukawa Electric Industrial Company, Ltd., Japan wherein an illuminating light is transmitted to the tip of a long insertable part by using a light guide of light conducting fibers to inspect a long pipe or the like, and the above mentioned insertable part can be housed as wound up on a drum. In such apparatus, a light source is fitted on a drum rotating shaft on the drum integrally with a frame of the drum and the optical axis of the light source and the optical axis of the light guide of fibers are made to coincide with each other to make the light of the above mentioned light source enter the light guide.
An illuminating apparatus provided with a fiber bundle windable on a drum is disclosed in the publication of a Japanese utility model application laid open No.9307/1987. However, in this illuminating apparatus, too, the light source is housed within the drum.
However, there are problems that, if the drum and light source are made integral with each other so as to be inseparable in use, the drum will be so large and heavy as to make it difficult to carry, position and operate it and that, as the light source can not be set in any desired position, the utility of the light source will be low.
Also, in the conventional drum, as the insertable is wound up on the outer periphery of the drum, if an insertable part having little flexibility is wound up on a drum of a small diameter, the bending rigidity will be so high that the wound insertable part will expand to have a large diameter. Generally, a long endoscope is used to inspect a pipe or the like and is inserted by pushing in the insertable part. The longer the insertable part, the farther the inserting operating point from the tip of the insertable Part. Due to the friction resistance of the tip, the insertable part will buckle and will become difficult to insert. Therefore, the longer the insertable part the more rigid the insertable part must be made.
Therefore, in the conventional drum, the longer the insertable part and the lower the flexibility, the larger the diameter of the drum must be and therefore the weight and lack of portability are problems.
Shown in the following are three examples of such apparatus wherein the insertable part can be wound up on a drum and an imaging means is provided.
The first example is an apparatus disclosed in the publication of a Japanese patent application laid open No. 164688/1981. As shown in FIG. 66, this apparatus has an image guide 1101 as an elongate insertable part and a drum for winding up this image guide and an objective lens 1103 is provided on the tip of the above mentioned image guide 1101 so that an object image formed by the objective lens 1103 may be transmitted into the drum 1102 by the image guide 1101 and may be imaged by a television camera 1105 provided within this drum 1102 and the image imaged by this television camera 1105 may be displayed in a monitor television 1106.
However, in this prior art example, the image guide is used, is a bundle of 10,000 to 30,000 fibers and has therefore a problem that the resolution is low. Also, as the image attenuated through the image guide is imaged by the television camera, there is a problem that the sensitivity will be low.
Therefore, such imaging apparatus as is shown in FIG. 67 is considered as the second example.
The apparatus of this second example has a cable 1111 as an elongate insertable part and a drum on which the cable 1111 can be wound up and a television camera 1112 is provided in the tip part of the above mentioned cable 1111. The above mentioned cable 1111 is led into the drum 1102 and is then extended out of the side of the drum 1102 This cable 1111 contains a current source line 1113 for feeding a current source for operating the above mentioned television camera 1112 and a signal line 1115 for delivering a video signal which is an output of the television camera 1112. The above mentioned current source line 1113 is connected to a current source unit 1114 outside the drum 1102 and the signal line 1115 is connected to a monitor television 1106 outside the drum 1102. The above mentioned television camera 1112 is formed as shown in FIG. 68. That is to say, the television camera 1112 has an objective lens 1107, a (solid state) imaging device 1108 arranged in the image forming position of this objective lens 1107 and a signal circuit part 1109 for operating this imaging device 1108 and outputting a video signal.
In this apparatus of the second example, an object is imaged directly by the television camera, 200,000 to 300,000 pixels are used in the television camera and are several tens times as many as in the image guide and therefore the resolution is high. However, there is a problem that the television camera 1112 has the signal circuit part 1109 and is therefore so large in size as not to be insertable into a fine tube or the like.
The third example is shown in the publication of a Japanes patent application laid open No.75315/1986. As shown in FIG. 69, this apparatus is provided with an elongate insertable part 1121 and a tip part 1122 containing only an objective lens, imaging device and supersmall electric parts is provided at the tip of this insertable part 1121. A camera controlling part 1152, light source part 1153 and monitor part 1154 are contained in a unit body 1151 which is not rotated of a drum unit. By the way, the insertable part 1121 is to be wound up on a rotatable rotary part 1156 provided on the outer peripheral part of the above mentioned unit body 1151.
In this apparatus, as the unit body 1151 is a part which is not rotated, a signal must be transmitted between the rotary part 1151 and unit body 1151. In the specification of the Japanese patent application laid open No.75315/1986, as shown in FIG. 70, an electric signal is to be transmitted between the rotary part 1156 and unit body 1151 through a curled cord 1159. However, there is a problem that the durability of the curled cord is low. A slip ring must be used.
An example of the structure of the above mentioned slip ring is shown in FIG. 71. In this slip ring 1133, a plurality of concentric circular electrodes 1143 are arranged on a plate 1142 not rotated together with a fixed shaft 1141 and electric wires U.sub.1, U.sub.2. . . U.sub.18 are connected to the respective electrodes 1143 and are connected to the unit body 1151. On the other hand, brush-like electrodes 1146 are provided to rotate and move together with a rotating cover 1145 and are in contact respectively with the above mentioned electrodes 1143. The respective brush-like electrodes 1143 are contacted with the imaging device. As illustrated, the above mentioned electrodes 1143 and 1146 are made, for example, 18 pairs respectively corresponding to signals t.sub.1 to t.sub.18. The details of these signals t.sub.1 to t.sub.2 are as illustrated. Among them, .phi.R, .phi.H.sub.4, .phi.H.sub.3, .phi.H.sub.2, .phi.H.sub.1, .phi.V.sub.4, .phi.V.sub.3, .phi.V.sub.2 and .phi.V.sub.1 are driving pulses required to operate the imaging device and PT, V.sub.sub and V.sub.DD are direct current voltages required to also operate the imaging device. V.sub.OUT and D.sub.MY are video signals output from the imaging device and delivered to a camera controlling unit 1152. G.sub.1 and G.sub.2 are earthing lines. The total of these necessary signal lines will be 16 poles even if options to be used for future expansion are excepted.
Thus, as in the apparatus of the third example, if the imaging device and signal circuit part are separated from each other, very many signal lines will have to be connected between them. Therefore, the slip ring 1133 will become large and very expensive. Further, the above mentioned pulses to operating the imaging device are of high frequencies and, if they are led to such exposed conductors as the poles 1143 and 1146, electromagnetic waves will be radiated in the space and will be likely to affect nearby televisions, radios and wireless instruments.
If the slip ring is between the imaging device and signal processing circuit, the noise mixed in by the slip ring will be amplified and the S/N ratio will be reduced.